From: Paul Chavent <Paul.Chavent@onera.fr>
Date: Fri, 3 Jan 2014 03:10:35 +0000 (+1100)
Subject: pps : add non blocking option to PPS_FETCH ioctl.
X-Git-Tag: next-20140106~2^2~9
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=15d1571cd5330e5a84f0aba0f29ddf13638e2566;p=karo-tx-linux.git

pps : add non blocking option to PPS_FETCH ioctl.

The PPS_FETCH ioctl is blocking still the reception of a PPS event.  But,
in some case, one may immediately need the last event date.  This patch
allow to get the result of PPS_FETCH if the device has the O_NONBLOCK flag
set.

Signed-off-by: Paul Chavent <paul.chavent@onera.fr>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Cc: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 2f07cd615665..983f50c4b7b4 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -152,35 +152,38 @@ static long pps_cdev_ioctl(struct file *file,
 		if (err)
 			return -EFAULT;
 
-		ev = pps->last_ev;
-
-		/* Manage the timeout */
-		if (fdata.timeout.flags & PPS_TIME_INVALID)
-			err = wait_event_interruptible(pps->queue,
-					ev != pps->last_ev);
-		else {
-			unsigned long ticks;
-
-			dev_dbg(pps->dev, "timeout %lld.%09d\n",
-					(long long) fdata.timeout.sec,
-					fdata.timeout.nsec);
-			ticks = fdata.timeout.sec * HZ;
-			ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
-
-			if (ticks != 0) {
-				err = wait_event_interruptible_timeout(
-						pps->queue,
-						ev != pps->last_ev,
-						ticks);
-				if (err == 0)
-					return -ETIMEDOUT;
+		if (!(file->f_flags & O_NONBLOCK)) {
+			ev = pps->last_ev;
+
+			/* Manage the timeout */
+			if (fdata.timeout.flags & PPS_TIME_INVALID)
+				err = wait_event_interruptible(pps->queue,
+						ev != pps->last_ev);
+			else {
+				unsigned long ticks;
+
+				dev_dbg(pps->dev, "timeout %lld.%09d\n",
+						(long long) fdata.timeout.sec,
+						fdata.timeout.nsec);
+				ticks = fdata.timeout.sec * HZ;
+				ticks += fdata.timeout.nsec /
+					(NSEC_PER_SEC / HZ);
+
+				if (ticks != 0) {
+					err = wait_event_interruptible_timeout(
+							pps->queue,
+							ev != pps->last_ev,
+							ticks);
+					if (err == 0)
+						return -ETIMEDOUT;
+				}
 			}
-		}
 
-		/* Check for pending signals */
-		if (err == -ERESTARTSYS) {
-			dev_dbg(pps->dev, "pending signal caught\n");
-			return -EINTR;
+			/* Check for pending signals */
+			if (err == -ERESTARTSYS) {
+				dev_dbg(pps->dev, "pending signal caught\n");
+				return -EINTR;
+			}
 		}
 
 		/* Return the fetched timestamp */